1. Field of Invention
The present invention relates to thalidomide derivatives, the method of producing thereof, and the application thereof as an active pharmaceutical ingredient.
2. Description of Related Arts
In 1953, thalidomide was synthesized and extensively used as a depressant and preventive medicine for vomiting in pregnant women. In the early 1960s, the serious reproductive toxicity had been identified. However, some of the properties of thalidomide, such as the inhibition in the releasing of Tumor Necrosis Factor-α (TNFα), anti-angiogenesis and anti-inflammatory characteristics, make it more effective in the treatment of erythema nodosum leprosum (ENL), cutaneous erythematosus lupes (Arch. Dermatol, 1993, Vol. 129 P. 1548-1550), persistent erythematosus lupes (The Journal of Rheumatology, 1989, 16, P. 923-92), Behcet's syndrome (Arch. Dermatol. 1990, vol. 26, P. 923-927), Crohn's disease (Journal of Pediatr. Gastroenerol. Nurt. 1999, vol. 28, P. 214-216) and rheumatoid arthritis (Journal of Rheumatology, 1988, vol. 25, P. 264-969). Furthermore, thalidomide has been extensively used in clinical trials for the treatment of malignant tumors when these tumors show strong angiogenesis and chemotherapy refractory. In 1998, the FDA of the United States approved the use of thalidomide for treating ENL. In addition, the reproductive toxicity of thalidomide has been completely controlled by birth-control, especially in those patients who are in critical condition. However, since thalidomide is only slightly soluble in water (0.012 mg/mL, Arch. Pharm., 321, 371 (1988)), the bioavailability of thalidomide was poor, and posed a barrier for the administration of thalidomide extra-gastrointestinally. Also, the pharmacological research of thalidomide was affected.
Snider et al. tried to improve the solubility of the thalidomide by directly linking amino acids onto it, although such method can generate compounds with increased water-solubility. Nonetheless, even if the water-solubility of some compounds even increase to 300 mg/ml (CN1215397A), these precursors of thalidomide were not stable in the water (Bioorganic and Med. Chem. 9 (5), 1297-1291, 2001), and can only be injected immediately after the solution was prepared. Dr. Eger's group had linked the thalidomide with p-dialkylamino benzoates and got their hydrochloride salts (DE 4211812 A1). Although the water solubility of these hydrochloride salts of the thalidomide derivatives are much higher than that of thalidomide, they are easy to be de-salted and precipitated out as their correspond bases from their aqueous solutions at pH 7.5, indicating a decrease of their water solubility in condition close to physiological pH.